Are clone scripts Legal or Illegal?

Are clone scripts Legal or Illegal?

Legal if developed using business model and logic/concept from the original source. Illegal if hacked or patented or its source code is copied from teh original website

Check this website they deliver best ready-made online food delivery script which is similar to eat24hours, GrubhubFood PandaJust Eat clone which is well optimised for both the web and mobile platform.

https://www.orderingsystemonline.com